I'd say 250 is a little warm try to get the temp to 180-190 even 200 differant rad or fan or pump. You need to set your timming to about 36* total at 3000 rpm run 8-14* inital an the rest in the dist. mech & vacume you may have to have the dist. recurved to work with the engine better. Without more info that is all I can say hope that helps Dave.